GRAFTON — A mosquito bite, with its ferocious itch and blotchy bump, might seem like an annoying but harmless part of summer. Most of the time, that's all it is.

But for people such as a 79-year-old Westboro resident and an otherwise healthy 20-year-old from Newton, who died after contracting Eastern equine encephalitis, or EEE, from a mosquito, those annoying bites can prove deadly.

Sam R. Telford III, an infectious disease expert and professor at Tufts University's Cummings School of Veterinary Medicine, recently spoke to a community group at the school about the need to "fight the bite."

Not only are many people unaware of or lax about taking simple precautions to protect themselves, such as using insect repellent, but communities have faced dwindling support for mosquito control programs — often as a result of efforts by what many public health specialists see as passionate but misinformed environmental activists.

Mr. Telford said, "A lot of people have this idea that mosquito-borne illness is like a strike of lightning ... That's not true."

He said individual and environmental precautions need to be taken to prevent contracting EEE or West Nile virus, which can also be debilitating. "There's no way to really predict where and when it might strike," he told the audience.

In the past 10 years, according to the state Department of Public Health, there have been 101 cases of West Nile virus infection reported in Massachusetts residents and 23 human cases of EEE resulting in at least 12 deaths. In 2012, seven people contracted EEE and three died, including the Westboro resident.

EEE is the most dangerous insect-borne virus in North America, with a 35 percent fatality rate.

"This is up there in the ball park with something like ebola," Mr. Telford said, referring to a deadly virus that causes hemorrhagic fever with fatality rates of 40 percent and higher.

Even people who survive the initial EEE illness can suffer long-term neurological damage that requires an average of $3 million per person for care.

EEE starts with flu-like symptoms but rapidly progresses to headaches, drowsiness, convulsions and coma. There is no specific treatment and no licensed vaccine for humans, although the U.S. Army has an experimental vaccine that appears to be effective.

Mr. Telford said the Army is researching prevention and treatment because the EEE virus could be used as a biological weapon.

EEE is seen predominantly in Southeastern, Central and recently Northeastern Massachusetts and New Hampshire, areas that are home to red maple and white cedar swamps. The swamps provide a breeding ground for mosquitoes, particularly cattail mosquitoes, that get the virus when they take a blood meal from birds and then transmit it to humans and horses.

Mr. Telford said the ecology of EEE seems to be changing, however, which some link to unintended consequences of storm water management. Since the U.S. Environmental Protection Agency began requiring retention ponds to control runoff, a major source of water pollution, the resulting artificial wetlands have become predator-free breeding grounds for mosquitoes.

Although not as deadly as EEE, West Nile virus may cause central nervous system disorders. Researchers are investigating a link between the virus and chronic kidney disease.

Although 80 percent of people with West Nile virus don't show immediate neurological symptoms, Mr. Telford said, "we can no longer look to 80 percent as reasons not to prevent West Nile disease."

West Nile virus is the most common vector-borne illness next to Lyme disease and is transmitted much like EEE, but typically by the mosquito species found around houses. They breed in gutters, garden containers, wading pools left with water and old tires — anywhere a quarter-inch or more of water might stand.

Mr. Telford serves as a commissioner of the Central Massachusetts Mosquito Control Project, overseen by the state Department of Agricultural Resources, which works with member communities to reduce breeding and proliferation of the 10 mosquito species found in the state.

When it uses pesticides, the project relies mainly on a few EPA-approved chemicals to kill larvae or, usually upon request of local residents, spray for adult mosquitoes. Synthetic pyrethroids, a copy of natural chemicals found in chrysanthemums, are generally used for adult mosquito control.

The chemicals have not been linked with cancer or birth defects and are considered to present the lowest risk to humans and other non-mosquito species. To reduce risk further to pollinators such as bees, EPA requires spraying only after sunset. Pyrethroids dissipate by the next day.

But it's the use of these chemicals, even low-risk ones, that has drawn a backlash from residents who claim that exposure harms humans and other animals.

Uxbridge town meeting voters shot down membership in the mosquito control project this year after a beekeeper raised the specter of potential danger to bees, which mosquito project representatives rebut. And at Grafton's fall town meeting, an article to resume membership in the mosquito project failed by 10 votes after a resident suggested his cancer was linked to mosquito spraying.

"We've tried twice to get the town back in," said Health Agent Lois Luniewicz. "It becomes a very emotional issue. It's very hard to combat emotion with fact."

"I would urge everyone to do their homework and evaluate the relevant literature," Mr. Telford said. "What is data and what is hearsay? It needs to undergo the scrutiny of peer review. There's no way to fight against emotional arguments."

A woman in the audience pointed out that homeowners buy these same chemicals at garden stores and spray them liberally around their properties.

Timothy D. Deschamps Sr., executive director of the mosquito control project, said, "What they (health officials) fight against is that 'more is better.'?" He said homeowners sometimes apply more than the recommended amount of pesticides, which could have unintended consequences.

With or without community mosquito control, Mr. Telford said, people could reduce their risk of mosquito-borne disease with the following measures:

◼?If you must be outdoors when mosquitoes are active, wear a long-sleeved shirt and long pants.

◼? Apply insecticide with permethrin to clothing (which also protects for ticks). Use insecticide with DEET — up to 15 percent concentration for children and 35 percent for adults — on your skin.

◼? Use mosquito netting on strollers and outdoor playpens.

◼? Fix holes in your screens and make sure they're tightly sealed.

◼?Remove sources of standing water around your home — turn over outdoor containers, clean gutters, remove old tires, and aerate or put fish in ornamental ponds because fish eat mosquito larvae.

And what doesn't work? Mr. Telford said citronella torches and ultrasonic zappers are largely a waste of money. And surprisingly, he said, "There's no scientific basis that bats, dragonflies, birds or other biocontrol have any effect at all."

The New York Times reported last week that an effective means of keeping mosquitoes away is a simple rotary fan: The wind pushes away the insects.

Contact Susan Spencer at susan.spencer@telegram.com. Follow her on Twitter @SusanSpencerTG.

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